Frank l



. No Drawing.

V strAtrns PATENT onnion.

FRANK L. DRIVER, J R., 0F NEWARK, NEW J ERs EY, AS SIGNOR TO ERIVERrH ARRIS COMPANY, OF HARRISON NEW JERSEY: A CORPORATION OF NEW JERSEY.

ELECTRIC-RESISTANCE ELEMENT AND ALLOY THIERIE'LEOR.

To all whom it may concern."

Be it known that I, FRANK L. DRIVER, J r., a citizen of the United States, residing at city of Newark,-county of Essex, State of New Jersey, have invented certainnew and useful Improvements in Electric-Resistance Elements and Alloy Therefor, of which the following is a full, clear, and exact descriptlon.

My invention relates to a new and improved electrical resistance element and an alloy therefor, and has for its object to provide a durable resistance element composed of a high heat resisting alloy having a high specific resistance resulting from the presence of substantial quantities of manganese and being of a permanent and uniform character. Heretofore it has been known that the addition of substantial quantities, of manganese to a nickel-iron alloy resulted in a marked increase in specific resistance. The nickel-iron-manganese alloy so formed was, however, very difiicult to manufacture into uniform resistance elements for the reason that during the various annealings of the metal for the purpose of enabling it to be drawn into yyires or rolled into plates the,

manganesetherein oxidized more or less so that the amount of manganese remammg 1n thealloy after it had been formed into wire or plate was uncertain and indefinite and the specific resistance varied in a corresponding manner. Furthermore, the manganeses of such an alloy oxidizes when the element is heated to a high heat while in use so that after the element has been formed its resistance during use becomes lower in the course of time on account of such oxidation.

I have discovered that by adding to the nickel-iron-manganese alloy a small. per

cent. of chromium the oxidation and loss of the manganese is practically prevented, the chromium acting as a stabilizer to stabilize the manganese not only during the time when the alloy is being worked into form but also when it is being subjected to high temperatures in ordinary use. For this purpose I have found that between one per cent. (1%) and two per cent. (2%) of chromium is. sufficient, and that when chromium to that extent is present in the iron-manganese-nickel alloy above referred to the manganese is well stabilized. In this way a resistance element having a high specific resistance which is permanent in its Specification of Letters latent. Patented N 11, 1919,

Application filed February 7, 1919. Serial No. 275,648. I I

character both during the working stage and during the period of use is obtained. The resistance element is also one which is very refractory in its character so that it has a long life even when highly heated. In making the above alloy I make the nickel contentabout fifty per cent. (50%), there being a zone in the neighborhood of fifty per cent. (50%) nickel and extending from aboutforty-five per cent. (45%) to fiftyfive per cent. (55%) in which considerable variations in the amount of nickel do not roduce substantial variations in resistance.

) and" I preferably use about ten per cent. (10%) although it may be increased to about twelve (12) or fourteen (14) per cent. Variations from eight per cent. (8%) to fourteen per cent. (14%) of manganese do not cause substantial changes in the specific resistance ofthe alloy produced, there being a zone within those limits in which the resistance due to the manganese content is approximately constant. As the manganese increases from fourteen. per cent. (14%) to eighteen per cent. (18%) the resistance rises uite rapidly and at about twenty per cent.

20%) the alloy becomes so brittle as to be unworkable. In commercial manufacture the resistance obtained by manganese between eight per cent. (8%) and fourteen per cent.

(14%) is sufficiently high for most purtions where the temperature of the element when in use does not exceed 1500? F. The

silicon should be kept as low as possible and the carbon should preferably not exceed .25 per cent. Cobalt may be substituted; for the nickel, it beingwell known that these two metals have common characteristics, and where I refer to a metal having the characteristics common to nickel or cobalt, I mean to refer to either of those metals.

The alloy whose composition I have specifically referred to above has a resistance of between 600 to 660 ohms per circular mil foot. It can be melted in either crucible or electric furnaces, cast into ingots, worked down under the hammer, rolled to Wire rod by a hot process and drawn cold through dies. It is malleable and ductile, and can be drawn into very fine Wire in a commercial manner.

In producing my alloy I preferably use an electric furnace the charge being made up so as to have the proper portions in the alloy and melted in the ordinary manner.

As will be evident to those skilled in the art, my invention permits of various modifications without departing from the spirit thereof or the scope of the appended claims. WVhat I claim is: I 1. An alloy comprising substantial proportions of iron, manganese, chromium and a metal having the characteristics common to nickel and cobalt, the percentage of the last named element lying within the approximately constant resistance zone including nickel fifty per cent. (50%), the percentage of the manganese lying within the approximately constant resistance zone including manganese ten per cent. (10%), and the percentage of chromium being low.

'2. An alloy comprising substantial proportions of iron, manganese, chromium and a metal having the character stlcs common to nickel and cobalt, the percentage of the last named element being between fortymanganese.

five per cent. and fifty-five per cent. (55%), the percentage of the manganese being between eight per cent. (8%) and fourteen per cent. (14%) and the percentage of chromium being less than half of the 3. An alloy comprisin iron, manganese, chromium and a metal aving the characteristics common to nickel and cobalt, the percentage of the last named. element being between forty-five per cent. (45%) and fiftyfive per cent. (55%), the percentage of the manganese being between eight per cent. (8%) and fourteen per cent. (14%) and the percentage of chromium being between one per cent. (1%) and two per cent. (2%). 4. An alloy comprisingiron, manganese, chromium and a metal having the characteristics common to nickel and cobalt, the percentage of the last named element being about fifty per cent. the manganese being about ten per cent. (10%) and the chromium about one and five-tenths per cent. (1.5%).

5. A resistance element composed of an alloy comprising substantial proportions of iron, manganese, a stabilizer for the manga nese consisting of a metal of the chromium group and a metal having the characteristics common to nickel and cobalt, the percentage of the last-named element lying within the approximately constant resistance zone in cluding fifty per cent. (50%), the percentage of manganese lying within the apIproXimately constant resistance zone inc uding ten per cent. (10%) and the percentage of the stabilizer being low.

FRANK L. DRIVER, JR. 

